1. Field of the Invention:
This present invention relates to a joist element for fastening a flat, plate-shaped structural element to a pitched roof, in particular for fastening a solar energy collection module, whereby the joist element, laid in the ridge-eaves direction, can be fastened to the roof substructure.
2. Background Information:
Such a system is described in German Patent No. 94 09 453.9 U1, for example. In this system, modules are arranged so that they overlap one another in the longitudinal direction of the roof. In this specification, the longitudinal direction is called the ridge-eaves line, and the transverse direction is designated a line parallel to the ridge or to the eaves. As the joist elements, there are wooden profiles laid in the edge-eaves direction which, on their ridge-side end, are in contact with a roof batten and on their eaves-side end are in contact with a wooden batten that is laid parallel to a roof batten and adjacent to the latter. The wooden batten projects beyond the upper edge of the roof batten by approximately the thickness of the module. The wooden profiles, on their surface, have a depression that runs in the longitudinal center, so that this depression, when located on the edges of two modules butted against one another, serves as a drain channel for the discharge of any water that may have penetrated into the gap. One disadvantage of this system is that additional wooden battens must be laid parallel to the roof battens, and that additional stays that are engaged around the eaves-side edge of the modules are necessary for fastening.